Breech-bolt checking construction for automatic firearms



NOV. 10, 1942. J BROWNING 2,301,248

BREECHBOLT CHECKING CONSTRUCTION FOR AUTOMATIC FIREARMS Filed March 21,1939 2 Sheets-Sheet l 1942. J. E. BROWNING BREECHBOLT CHECKINGCONSTRUCTION FOR AUTOMATIC FIREARMS Filed March 21, 1959 2 Sheets-Sheet2 Patented Nov. 10, 1942 BREECH-BOLT CHECKING CONSTRUCTION FOR AUTOMATICFEREARMS Jonathan E. Browning, Ogden, Utah, assignor to WesternCartridge Company,

New Haven,

2 Claims.

This invention relates to improvements in automatic firearms and relatesmore particularly to a construction and arrangement of parts whereby thebreech-bolt and associated parts (commonly referred to as thefirearm-action) have their rearward travel (occasioned by the dischargeof the firearm) checked or stopped in an improved manner.

One of the objects of the present invention is to provide an automaticfirearm with a superior construction and arrangement of parts wherebythe rearward travel of the breech-bolt and associated parts is checkedor stopped without undue strain and wear upon the parts.

A further object of the present invention is to provide an automaticfirearm with superior means whereby the rearward travel of thebreechbolt and associated parts is effectively checked withoutoccasioning the rapid rebound thereof.

Another object of the present invention is to provide a superior andreliable automatic firearm-construction wherein the rearward travel ofthe breech-bolt and associated parts, following the discharge of thefirearm, is effectively but gradually checked or stopped preparatory tothe return movement of the said breech-bolt and its associated parts totheir normal positions.

A still further object of the present invention is to provide a superiorautomatic firearm-construction wherein the return movement of thebreech-bolt and associated parts to their normal positions, after havingbeen operated by the discharge of the firearm, is sufiiciently delayedor retarded to permit the complete ejection of the just-fired shell andthe proper positioning of a fresh cartridge preparatory to the automatic1nsertion of such fresh cartridge into the cartridgechamber of thefirearm.

With the above and other objects in View, as will appear to thoseskilled in the art from the present disclosure, this invention includesall features in the said disclosure which are novel over the prior artand which are not claimed in any separate application.

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

Fig. 1a is a broken view partly in side elevation and partly invertical, central, longitudinal section of the rear portion of anautomatic firearm embodying the present invention;

Fig. 1b is a similar view of the forward portion of the firearm;

Fig. 2 is a view corresponding to Fig. la. but

when the firearm-action is in its rearmost position immediatelyfollowing the discharge of the firearm;

Fig. 3 is a fragmentary view in vertical, central, longitudinal sectionof the portion of the firearm immediately adjacent the junction of thebuttstock-portion and the rear portion of the receiver, and showing theparts in the positions in which they are shown on a smaller scale inFig. 2;

Fig. 4 is a transverse sectional view taken on the line l-S of Fig. 3;

Fig. 5 is a broken view in side elevation of the rear portion of thereceiver and the forward portion of the receiver-extension;

Fig. 6 is a transverse sectional view taken on the line E-S of Fig. 5;

Fig. 7 is a broken view in side elevation of the rear portion of theaction-slide; and

Fig. 8 is a rear elevation thereof.

The particular automatic firearm herein chosen for the purpose ofillustrating the present invention is of the gas-operated type, in whichthe gas pressure developed by the firing of a cartridge is utilized toefiect the rearward travel of the breech-bolt, accompanied by theextraction and ejection of the just-fired cartridge preparatory to thereturn movement of the said breech-bolt to effect the reloading of thefirearm with a fresh cartridge in readiness for again discharging thefirearm.

The automatic firearm shown in the accompanying drawings includes areceiver l0 rigidly secured at its forward end to the adjacent rearportion of a barrel H, which latter is provided with the usual axialbore l2 through which the bullets are forwardly propelled in the usualmanher of firearms. Attached to the receiver l0 and the barrel Ii is astock I3 preferably formed of Wood or other heat-insulating andshock-absorbing material.

The stock [3, just above referred to, includes a buttstock-portion l4and a forestock-portion l5, both of which are integrally united witheach other, though, if desired, a separate buttstock and a separateforestock may be employed, in accordance with common practice in firearmconstructions.

The receiver 19 is provided in its interior with a longitudinalbolt-receiving chamber IS in which is adapted to reciprocate, in anyapproved manner, a breech-bolt ll, not requiring detailed descriptionherein. The bolt-receiving chamber IB, just referred to, is flanked oneach of its respecshowing the positions which the parts assume tiveopposite sides by side walls l8--|8 depending from a top wall it of thereceiver it and skeletonized at their rear portions by apertures 20 toreduce the over-all weight of the said receiver. As will be seen byreference to Figs. 1a and 2, the top wall iii of the receiver iii is cutaway at its forward portion to accommodate the upper portion of thebreech-bolt i? when the same is in its closed position, and to provide alocking-abutment 2! which faces forwardly and which is adapted to beengaged by a rearwardly facing locking-abutment 22 formed upon the upperrear portion of the breech-bolt ii.

The extreme rear portion of the receiver ii] is formed integrally with adepending L-shap'ed arm generally designated by the reference character23 and comprising a substantially-vertical reach as and asubstantially-horizontal forwardly-extending reach 25.

The substantially-vertical reach 2 3 of the L- shaped arm 23 at the rearend of the receiver It is provided with a threaded bore 26 receiving theexternally threaded forward end of a tubular receiver-extension 27having at its rear end a relatively-thick end-wall 26. The said end-wallis provided with an axial threaded passage receiving' the adjacentthreaded end of a screw 28 extending forwardly at a slightlyupwardly-inclined angle through a similarly inclined passage 52% formedin the buttstock-portion It. The extreme rear or head-end of the screw28 is seated in a suitable recess in a buttplate 3i mounted against thebutt-end of the buttstock-portion M as indicated in Figs. 1a and 2-.

The tubular receiver-extension 1 is accommodated in a bore '32 formed inthe buttstockto, constitutes a rigid extension of a cross-head 7 36forming the rear part of an action-slide generally designated by thereference character 31?, and

including also two. parallel laterally-spaced-apart side-bars 3$iiextending in substantial parallelis'm with the axis of thereceiver-extension 27,.

Each of thesaid side-bars is adapted to reciprocate, in a manner as willhereinafter appear, against the lower edge 3% of the adjacent one of thetwo side-walls I3i8 of the receiver It, and against an upwardly-facingsupporting-ledge 49 forming a feature of the adjacent side-arm ti, oneof which latter depends from each of the sidewalls l-'Sl3 of thereceiver I'll.

At their forward ends, each of the side-bars 3833 of the action-slide 3?are pivotally connected by means of a screw 42 to the rear end of anactuating-rod 53. The said actuating-rod 43 reciprocates beneath thebarrel H and extends through a clearance-passage 44 formed in abarrel-lug t integrally formed with and depending from the barrel I l.Immediately below the lower end of the barrel-lug 65, theforestock-portion I5 is provided in its under face with an escutcheon4'6 through which upwardly projects an attaching-screw l'i extendinginto threaded engagement with the barrel-lug d5. The'lower portion ofthe barrel-lug 55 fits into an upwardly-opening socket 3 intersecting atits upper end a longitudinal recess 49 formed in the upper face of theforestock-portion I5 and accommodating, in addition to a portion of thebarrel II, the forward portion of the action-slide 31 and the rearportion of the actuating-rod 43, as is clearly indicated in Fig. 1b.

The forward end of the actuating-rod 33 is integrally formed orotherwise attached to a tubular-piston 50 which encircles the barrel Hand which is adapted to reciprocate thereon in a manner as will morefully hereinafter appear. The forward edge of the tubular-piston 50 is 3formed with a notch 5i which is normally in registration with the outerend of a gas-port 52 extending radially through the barrel H from itsbore I2 to its outer periphery, to provide for the conduction ofgas-under-pressure to the forward end of the tubular-piston til.

Surrounding the exterior of the tubular-piston 58 when the same is inits forward'position, is the rearwardly-extending skirt 53 of a cylinder5%. Said cylinder 54 is formed with an internally-threadedforward-portion 55 threaded onto a threaded-portion 56 of the barrel II. so as to be adjustable longitudinally with respect to the said barrelfor the purpose of covering or uncovering more or less of the outer endof the gas-port 52.

The skirt 53 constituting the rear portion of the cylinder 5 has itsinner surface spaced from the adjacent exterior surface of the barrel Hto a degree sufiicient to accommodate, with a free sliding fit, thetubular-piston 59 before referred to. In conjunction with the adjacentsurface of the barrel ii, the inner surface of the skirt 53 provides atubular gas-chamber 5? in which. the tubular-piston 5B is normallylocated.

For the purpose of enabling the action-slide 31 and its associated partsto be manually moved rearwardly in lieu of its automatic movement, theright-hand one of the. two side-bars 38-38 of the said action-slide haspivotally connected to it by means of a stud 58,, the lower end of asubstantially-vertical arm 5'9 of an L-shaped link 40. The said L-shapedlink Gil also includes a relatively-long substantially-horizontal arm 6|reciprocating in a guide-way 6.2 formed in the adjacent side-wall of thereceiver Ill and is provided at its rear end with a knob or operatinghandle 6.3 as is indicated in Figs. la and 2. Pivotally attached to therear cross-head. 3,6 of the actionslide El by means, of a pivot-pin H isthe lower end of a breech-bolt-operatinglink 64 which, in turn, has, itsupper end pivotal-1y connected by means of a pivot-pin 18 to the lowerrear por-.

tion of the breech-bolt I! which latter is mounted for tiltingv andreciprocating movement in the bolt-receiving chamber 16 in the receiverIt as is indicated in Figs. 1a and 2.

Considering now the primary means whereby the rearward movement of thefirearm-action is checked, it will be noted by reference to Figs. 3 to 5inclusive in particular, that the upper surface of the, horizontal.reach 25 of the L-shaped arm 23 of the receiver it is formed with achecking-surface t5 which is inclined forwardly and downwardly withrespect to the complemental checking-surface 66 formed by the particularportion of the under face of the receiver H3 which is located justforward-ly'of the junction of the L-shaped arm 23 with the receiver i=0proper, as is indicated particularly well in Fig. 5.. The angularrelationship between the checking-surfaces 65 and 66, just referred to,may vary under dif- 'fere'nt conditions, but in the particular instanceillustrated, approximately a seven degree departure from parallelism hasbeen found to be satisfactory.

By reference to Figs. 7 and 8, in particular, it will be observed thatthe upper surface of the cross-head 36 and the adjacent upper surfacesof the side-bars 33-38 of the action-slide 3'! constitute achecking-surface El engageable with the checking-surface 66 of thereceiver it, while the under face of the said cross-head 3t constitutesa checking-surface 6B engageable With the checking-surface (55 of thehorizontal reach 25 of the L-shaped arm 23. The engagement of therespective checking-surfaces just referred to, is clearly shown in Figs.2, 3 and 4.

As will be seen by reference to Figs. 1a, 2 and 3 in particular, theunder face of the L-shaped arm 23 of the receiver I is provided with atransverse locating-groove 69 which receives a locating-rib i8upstanding from the rear portion of a trigger-plate l i. The said rearportion of the trigger-plate H is secured to the receiver It by means ofan attaching-screw 12 extending upwardly through the trigger-plate H andinto a threaded bore 13 (Fig. 3) in the horizontal reach 25 of theL-shaped arm 23.

About midway of its length the trigger-plate H is formed with anintegral loop-like triggerguard W in which is located a trigger 15 bymeans of which latter the firearm may be discharged in any suitablemanner, such, for instance, as is shown and described in my copendingapplication Ser. No. 136,523, filed April 13, 1937.

The forward end of the trigger-plate H is formed with anattaching-finger l6 which is secured in any suitable manner to theadjacent portion of the receiver if! and which overlies the adjacentportion of the bottom wall of the forestock-portion i5, as shown inFigs. la and 2.

In order to make clear the operation of the automatic firearm abovedescribed and illustrated in the accompanying drawings, let it beassumed that the firearm is loaded preparatory to being fired and thatthe tubular-piston 56 and the connected parts are in their forwardpositions as indicated in Figs. 1a and It).

With the parts in the position just above referred to, when the triggerI is pulled the firearm will be discharged with the result that theprojectile or bullet will be propelled forwardly through the bore I2 ofthe barrel II and gasunder-pressure will pass radially outwardly fromthe said bore i2 through the gas-port 52 into the forward end of thegas-chamber 51 with the result that the tubular-piston 5?] will receivea rearward kick so to speak.

The rearward movement of the tubular-piston 50 will correspondingly movethe actuating-rod 43, action-slide Si, spring-guiding plunger 35 and theassociated parts. The rearward movement of the action-slide 37 willcompress the breechclosing spring 3-3 in the tubular receiver-extension21 and will, through the intermediary of the link 64, first rock therear end of the breechbolt l1 downwardly to disengage itslockingabutment 22 from the locking-abutment 2| of the receiver 19,following which the said breechbolt will be moved bodily rearwardly inthe boltreceiving chamber [6 of the said receiver l0 and will effect theextraction and ejection of the justfired cartridge.

As the action-slide 3i nears the completion of its rearward movement,the checking-surfaces 61 and 63 at its rear end will be brought intowedging engagement with the complemental checking-surfaces 65 and 66 atthe rear end of the receiver I0 as is shown in Figs. 2 and 3. Theengagement of the checking-surfaces as just described will serve tocheck the rapid rearward movement of the action-slide and its associatedparts without occasioning deformation of the parts and without causing arapid rebound such as might so rapidly close the breech-bolt H as tocause the same to jam against a fresh cartridge while the same isenroute into the cartridge-chamber of the barrel H.

Owing to its resilient character, the horizontal reach 25 of theL-shaped arm 23 of the receiver is will yield sufficiently as thechecking-surfaces above referred to come into engagementin the mannerdescribed to further assist in relatively gradually checking therearward movement of the action-slide 31 and its connected parts, and inavoiding an objectionable rebound of the firearm-action.

After having been moved rearwardly as above described, the action-slide3? and its connected parts, including the breech-bolt i1, will be movedforwardly under the urge of the breech-closing spring 33 to effect theinsertion of a fresh cartridg into the cartridge-chamber of the firearmand the closing and locking of the breech-bolt l1, preparatory to againdischarging the firearm. The parts will now have again assumed thepositions in which they are shown in Figs. 1a and 1b.

By so constructing and arranging the parts that the rearward movement ofthe breech-bolt and its associated parts is checked without undue shock,not only are the parts spared the almost inevitable deformation andexcessive wear, but one of the major problems connected with automaticfirearms is effectively solved inasmuch as the rebound of thebreech-bolt and its associated parts is so minimized or obviated as toavoid the danger of the breech-bolt closing so rapidly as to impingeagainst a fresh cartridge while the same is enroute into thecartridgechamber of the barrel H or its equivalent.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

I claim:

1. An automatic firearm including in combination: a receiver formed atits rear end with a depending L-shaped arm extending below the underface of the receiver proper and comprising a substantially-verticalreach and a substantially-horizontal reach integral with and extendingforwardly from the lower end of the said substantially-vertical reach inspaced relationship below the under face of the receiver proper, theupper face of the said substantially-horizontal reach being slopedforwardly and downwardly from the said substantially-vertical reach andfacing upwardly toward the under face of the receiver proper, the upperface of the said substantially-horizontal reach and the under face ofthe receiver proper together defining a forwardly-expanding wedge-shapedrecess; a breech-bolt reciprocating in the said receiver; anaction-slide operatively connected to the said breech-bolt and formed atits rear with a wedgethe L-shaped arm of the said receiver and having anupper face extending substantially parallel and engaging with the underface of the said receiver when the action-slide is retired rearwardly,the said action-slide also having an under face extending substantiallyparallel and engaging with the sloping upper face of the saidsubstantially-horizontal reach of the L-shaped arm of the said receiverwhen the action-slide is retired rearwardly; and spring-means urging thesaid action-slide forwardly away from the L-shaped arm of the saidreceiver.

2. An automattic firearm including in combination: a receiver formed atits rear end with a depending L-shaped arm extending below the underface of the receiver proper and comprising a substantially-verticalreach formed intermediate its upper and lower ends with a passageleading substantially horizontally from the front to the rear thereof,the said L-shaped arm also including a substantially-horizontal reachintegral with and extending forwardly from the lower end of the saidsubstantially-vertical reach in a plane below the said passage, theupper face of the said substantially-horizontal reach being slopedforwardly and downwardly from the said substantially-vertical reach andfacing upwardly upper face of the said substantially-horizontal shapedportion normally spaced forwardly from reach and the under face of thereceiver proper together defining a forwardly-expanding Wedgeshapedrecess; a breech-bolt reciprocating in the said receiver; anaction-slide operatively connected to the said breech-bolt and formed'atits rear with a wedge-shaped portion normally spaced forwardly from theL-shaped arm of the said receiver and having an upper face extendingsubstantially parallel and engaging with the under face of the saidreceiver when the actionslide is retired rearwardly, the saidaction-slide also having an under face extending substantially paralleland engaging with the sloping upper face of the saidsubstantially-horizontal reach of the L-shaped arm of the said receiverwhen the action-slide is retired rearwardly; a spring-guiding plungerextending rearwardly from the said action-slide in a plane intermediatethe under face of the receiver proper and the sloping upper face of thesubstantially-horizontal reach of the L-shaped arm at the rear of thesaid receiver; and a helical breech-closing spring extending through thepassag in the substantially-vertical reach of the L-shaped arm of thesaid receiver and over the spring-guiding plunger of the saidaction-slide and yieldingly urging the said action-slide forwardly awayfrom the L-shaped arm at the rear end of the said receiver.

JONATHAN E. BROWNING.

